Masanori Yoshimatsu

Overexpression of LSD1 contributes to human carcinogenesis through chromatin regulation in various cancers

A number of histone demethylases have been identified and biochemically characterized, but the pathological roles of their dysfunction in human disease like cancer have not been well understood. Here, we demonstrate important roles of lysine‐specific demethylase 1 (LSD1) in human carcinogenesis. Expression levels of LSD1 are significantly elevated in human bladder carcinomas compared with nonneoplastic bladder tissues (p < 0.0001). cDNA microarray analysis also revealed its transactivation in lung and colorectal carcinomas. LSD1‐specific small interfering RNAs significantly knocked down its expression and resulted in suppression of proliferation of various bladder and lung cancer cell lines. Concordantly, introduction of exogenous LSD1 expression promoted cell cycle progression of human embryonic kidney fibroblast cells. Expression profile analysis showed that LSD1 could affect the expression of genes involved in various chromatin‐modifying pathways such as chromatin remodeling at centromere, centromeric heterochromatin formation and chromatin assembly, indicating its essential roles in carcinogenesis through chromatin modification.

Dysregulation of PRMT1 and PRMT6, Type I arginine methyltransferases, is involved in various types of human cancers

Protein arginine methylation is a novel post‐translational modification regulating a diversity of cellular processes, including histone functions, but the roles of protein arginine methyltransferases (PRMTs) in human cancer are not well investigated. To address this issue, we first examined expression levels of genes belonging to the PRMT family and found significantly higher expression of PRMT1 and PRMT6, both of which are Type I PRMTs, in cancer cells of various tissues than in non‐neoplastic cells. Abrogation of the expression of these genes with specific siRNAs significantly suppressed growth of bladder and lung cancer cells. Expression profile analysis using the cells transfected with the siRNAs indicated that PRMT1 and PRMT6 interplay in multiple pathways, supporting regulatory roles in the cell cycle, RNA processing and also DNA replication that are fundamentally important for cancer cell proliferation. Furthermore, we demonstrated that serum asymmetric dimethylarginine (ADMA) levels of a number of cancer cases are significantly higher than those of nontumor control cases. In summary, our results suggest that dysregulation of PRMT1 and PRMT6 can be involved in human carcinogenesis and that these Type I arginine methyltransferases are good therapeutic targets for various types of cancer.

Overexpression of the JmjC histone demethylase KDM5B in human carcinogenesis: involvement in the proliferation of cancer cells through the E2F/RB pathway

BackgroundAlthough an increasing number of histone demethylases have been identified and biochemically characterized, their biological functions largely remain uncharacterized, particularly in the context of human diseases such as cancer. We investigated the role of KDM5B, a JmjC histone demethylase, in human carcinogenesis. Quantitative RT-PCR and microarray analyses were used to examine the expression profiles of histone demethylases in clinical tissue samples. We also examined the functional effects of KDM5B on the growth of cancer cell lines treated with small interfering RNAs (siRNAs). Downstream genes and signal cascades induced by KDM5B expression were identified from Affymetrix Gene Chip experiments, and validated by real-time PCR and reporter assays. Cell cycle-dependent characteristics of KDM5B were identified by immunofluorescence and FACS.ResultsQuantitative RT-PCR analysis confirmed that expression levels of KDM5B are significantly higher in human bladder cancer tissues than in their corresponding non-neoplastic bladder tissues (P < 0.0001). The expression profile analysis of clinical tissues also revealed up-regulation of KDM5B in various kinds of malignancies. Transfection of KDM5B-specific siRNA into various bladder and lung cancer cell lines significantly suppressed the proliferation of cancer cells and increased the number of cells in sub-G1 phase. Microarray expression analysis indicated that E2F1 and E2F2 are downstream genes in the KDM5B pathway.ConclusionsInhibition of KDM5B may affect apoptosis and reduce growth of cancer cells. Further studies will explore the pan-cancer therapeutic potential of KDM5B inhibition.

Demethylation of RB regulator MYPT1 by histone demethylase LSD1 promotes cell cycle progression in cancer cells.

Histone demethylase LSD1 (also known as KDM1 and AOF2) is active in various cancer cells, but its biological significance in human carcinogenesis is unexplored. In this study, we explored hypothesized interactions between LSD1 and MYPT1, a known regulator of RB1 phosphorylation. We found that MYPT1 was methylated in vitro and in vivo by histone lysine methyltransferase SETD7 and demethylated by LSD1, identifying Lys 442 of MYPT1 as a target for methylation/demethylation by these enzymes. LSD1 silencing increased MYPT1 protein levels, decreasing the steady state level of phosphorylated RB1 (Ser 807/811) and reducing E2F activity. MYPT1 methylation status influenced the affinity of MYPT1 for the ubiquitin-proteasome pathway of protein turnover. MYPT1 was unstable in murine cells deficient in SETD7, supporting the concept that MYPT1 protein stability is physiologically regulated by methylation status. LSD1 overexpression could activate RB1 phosphorylation by inducing a destabilization of MYPT1 protein. Taken together, our results comprise a novel cell cycle regulatory mechanism mediated by methylation/demethylation dynamics, and they reveal the significance of LSD1 overexpression in human carcinogenesis.

Lysyl 5-Hydroxylation, a Novel Histone Modification, by Jumonji Domain Containing 6 (JMJD6)

Background: JMJD6 hydroxylates U2AF65, but its role in histone modification has been obscure. Results: Our analysis of histones purified from JMJD6 knock-out mouse embryos reveals that JMJD6 hydroxylates histone lysyl residues. Conclusion: JMJD6 mediates histone lysyl 5-hydroxylation, which is a novel histone modification. Significance: Our study identifies a new function for Jumonji family proteins in epigenetic modification of histones. JMJD6 is reported to hydroxylate lysyl residues of a splicing factor, U2AF65. In this study, we found that JMJD6 hydroxylates histone lysyl residues. In vitro experiments showed that JMJD6 has a binding affinity to histone proteins and hydroxylates multiple lysyl residues of histone H3 and H4 tails. Using JMJD6 knock-out mouse embryos, we revealed that JMJD6 hydroxylates lysyl residues of histones H2A/H2B and H3/H4 in vivo by amino acid composition analysis. 5-Hydroxylysine was detected at the highest level in histones purified from murine testis, which expressed JMJD6 at a significantly high level among various tissues examined, and JMJD6 overexpression increased the amount of 5-hydroxylysine in histones in human embryonic kidney 293 cells. These results indicate that histones are additional substrates of JMJD6 in vivo. Because 5-hydroxylation of lysyl residues inhibited N-acetylation and N-methylation by an acetyltransferase and a methyltransferase, respectively, in vitro, histone 5-hydroxylation may have important roles in epigenetic regulation of gene transcription or chromosomal rearrangement.

Minichromosome Maintenance Protein 7 is a potential therapeutic target in human cancer and a novel prognostic marker of non-small cell lung cancer

BackgroundThe research emphasis in anti-cancer drug discovery has always been to search for a drug with the greatest antitumor potential but fewest side effects. This can only be achieved if the drug used is against a specific target located in the tumor cells. In this study, we evaluated Minichromosome Maintenance Protein 7 (MCM7) as a novel therapeutic target in cancer.ResultsImmunohistochemical analysis showed that MCM7 was positively stained in 196 of 331 non-small cell lung cancer (NSCLC), 21 of 29 bladder tumor and 25 of 70 liver tumor cases whereas no significant staining was observed in various normal tissues. We also found an elevated expression of MCM7 to be associated with poor prognosis for patients with NSCLC (P = 0.0055). qRT-PCR revealed a higher expression of MCM7 in clinical bladder cancer tissues than in corresponding non-neoplastic tissues (P < 0.0001), and we confirmed that a wide range of cancers also overexpressed MCM7 by cDNA microarray analysis. Suppression of MCM7 using specific siRNAs inhibited incorporation of BrdU in lung and bladder cancer cells overexpressing MCM7, and suppressed the growth of those cells more efficiently than that of normal cell strains expressing lower levels of MCM7.ConclusionsSince MCM7 expression was generally low in a number of normal tissues we examined, MCM7 has the characteristics of an ideal candidate for molecular targeted cancer therapy in various tumors and also as a good prognostic biomarker for NSCLC patients.

The Histone Demethylase JMJD2B Plays an Essential Role in Human Carcinogenesis through Positive Regulation of Cyclin-Dependent Kinase 6

Histone methyltransferases and demethylases are known to regulate transcription by altering the epigenetic marks on histones, but the pathologic roles of their dysfunction in human diseases, such as cancer, still remain to be elucidated. Herein, we show that the histone demethylase JMJD2B is involved in human carcinogenesis. Quantitative real-time PCR showed notably elevated levels of JMJD2B expression in bladder cancers, compared with corresponding nonneoplastic tissues (P < 0.0001), and elevated protein expression was confirmed by immunohistochemistry. In addition, cDNA microarray analysis revealed transactivation of JMJD2B in lung cancer, and immunohistochemical analysis showed protein overexpression in lung cancer. siRNA-mediated reduction of expression of JMJD2B in bladder and lung cancer cell lines significantly suppressed the proliferation of cancer cells, and suppressing JMJD2B expression lead to a decreased population of cancer cells in S phase, with a concomitant increase of cells in G1 phase. Furthermore, a clonogenicity assay showed that the demethylase activity of JMJD2B possesses an oncogenic activity. Microarray analysis after knockdown of JMJD2B revealed that JMJD2B could regulate multiple pathways which contribute to carcinogenesis, including the cell-cycle pathway. Of the downstream genes, chromatin immunoprecipitation showed that CDK6 (cyclin-dependent kinase 6), essential in G1–S transition, was directly regulated by JMJD2B, via demethylation of histone H3-K9 in its promoter region. Expression levels of JMJD2B and CDK6 were significantly correlated in various types of cell lines. Deregulation of histone demethylation resulting in perturbation of the cell cycle, represents a novel mechanism for human carcinogenesis and JMJD2B is a feasible molecular target for anticancer therapy. Cancer Prev Res; 4(12); 2051–61. ©2011 AACR.

Risk factors that increase mortality after living donor liver transplantation.

Background. Female liver to male recipient is a well-accepted risk factor for graft loss in cadaveric liver transplantation. However, gender matching is infeasible because of an insufficient number of available donors. No studies have been performed on the role of gender in the field of living donor liver transplantation. This report investigates the effect of gender mismatch on the outcome of living donor liver transplantation. Methods. A total of 335 patients and donors were classified into four groups according to the following gender combinations: male donor to male recipient group (n=104), male donor to female recipient group (n=120), female donor to male recipient (FM) group (n=59), and female donor to female recipient group (n=52). Patient and graft survival were compared among the groups. We performed a multivariable analysis to identify the factors associated with patient mortality. Results. The 1-, 3-, 5-, and 10-year patient survival rates in the FM group were 80.6%, 66.8%, 61.8%, and 47.7%, respectively. The FM group showed significantly shorter patient survival compared with the other three groups. Independent risk factors for patient mortality were: FM group (P=0.006), pretransplant diabetes mellitus (P=0.001), and a model for end-stage liver disease score more than or equal to 20 (P=0.004). Conclusions. Male recipients of transplants from female donors, pretransplant diabetes mellitus, and a model for end-stage liver disease score more than or equal to 20 have poor survival rates.

Beneficial effects of supplementation with branched‐chain amino acids on postoperative bacteremia in living donor liver transplant recipients

The aim of this study was to investigate the effects of preoperative oral supplementation with branched‐chain amino acids (BCAAs) on postoperative bacteremia after living donor liver transplantation (LDLT) for chronic liver failure. Two hundred thirty‐six patients who underwent adult‐to‐adult LDLT were evaluated in this retrospective study. The patients were divided into 2 groups: those who received oral supplementation with BCAAs before transplantation (the BCAA group; n = 129) and those who did not (the non‐BCAA group; n = 107). Before the LDLT indication was determined, BCAA supplementation was prescribed by a hepatologist to preserve hepatic reserves. The clinical characteristics and the incidence of bacteremia were compared between the 2 groups. As for clinical characteristics, the Child‐Pugh scores (P = 0.0003) and the Model for End‐Stage Liver Disease scores (P = 0.0008) were significantly higher in the BCAA group versus the non‐BCAA group. The incidence of bacteremia for Child‐Pugh class C patients was significantly lower in the BCAA group (6/90 or 6.7%) versus the non‐BCAA group (11/50 or 22.0%, P = 0.0132). In a multivariate analysis, non‐BCAA supplementation was an independent risk factor for bacteremia. In conclusion, preoperative BCAA supplementation might reduce the incidence of bacteremia after LDLT. Nevertheless, this is a preliminary report, and further studies, such as randomized, prospective studies, are necessary to clarify the beneficial effects of BCAA supplementation on postoperative bacteremia after liver transplantation. Liver Transpl 17:1073–1080, 2011.

Granulocyte colony-stimulating-factor-producing hepatocellular carcinoma with extensive sarcomatous changes: report of a case

This report describes a rare case of hepatocellular carcinoma (HCC) producing granulocyte colony-stimulating factor (G-CSF). A 46-year-old male with chronic hepatitis B, who presented with fever, general malaise, loss of appetite, and weight loss, had a huge liver mass in the portal region. He had marked granulocytosis and his serum level of G-CSF was elevated. Complete tumor resection was performed, and the pathological assessment of the resected specimen revealed HCC with extensive sarcomatous changes and immunohistochemical staining for G-CSF and G-CSF receptor. Only a few cases of G-CSF-producing HCC have been reported, and this is the first case of G-CSF-producing HCC that also expressed G-CSF receptor.